It helps that you folks over there don't have 89 guns for every 100 people or a fairly large set of demographics that (not without reason) hate and fear police.
I mentioned this before, but it's essentially a self-perpetuating cycle at this point. A lot of people are raised to be scared of and distrust cops (and, in other words, are more likely to flee or resist) and cops are trained to be hyperaware of the potential that they could be attacked or killed in even routine interactions over minor infractions and that the appropriate way to avert that risk is to maintain total control of confrontations. So you've got cops who don't feel like they belong to the populations that they're supposed to be protecting and serving and citizens who see cops as hostile intruders in their communities.
That is, I suspect, how more than a few of these shootings happen: both parties are scared that the other is going to try to hurt or kill them for no reason.
Incidentally, that's one of the main issues I have with the popular position on police violence, the massively hypocritical double standard. Black men commit a vastly disproportionate number of violent crimes, and that's treated as exclusively a social issue, often completely ignoring the fact that there was still a choice made to commit those crimes (not to diminish the impact of poverty, the CIA's efforts to flood U.S. cities with hard drugs and the fallout from that, &c.). But when police are unnecessarily violent and too ready to use lethal force, that's thrown out the window. None of the social conditioning imposed on them matters, they're just racist shitheads willing to ruin their lives to kill some guy they don't know from Adam.
That's why I have a problem with the regressive left's approach to the problem of police brutality, as with so many other things. It's a clusterfuck of hypocrisy that ignores all nuance in favor of establishing a hierarchy of victimhood. Yeah, protest like hell about this bullshit, it's completely fucked up that U.S. cops do this. But trying to resolve it on a case-by-case punishment after-the-fact basis is about as pointless as trying to reduce the incidence of violent crime with harsher prison sentences and fewer opportunities for released felons. The root of the problem is the fearful, militarized police culture which has very strong ties to the cultures of police hatred and gun-worship; so long as guns are freely available to criminals and anti-government nuts and more than a few subsets of the population hate and fear police, they'll continue to justify their treatment of U.S. citizens as enemies and streets as battlefields. So long as police continue to kill people for little or no reason, those same populations will continue to justify their negative attitudes toward police.
This is what I've been getting at. It's not something that you can band-aid patch. It's a serious, complex social ill which is closely tied to numerous other fundamental issues with criminal law, weapon ownership, and class divisions. Beating up protestors, closing ranks on post-shooting investigations, calling cops racists for following their training and permissive local/state laws about the use of force, murdering cops on the streets/in their homes? None of that does shit to solve anything, but it serves to obfuscate the real issues and make self-serving assholes feel good about themselves while also making it even more difficult to institute the sort of multi-front comprehensive changes that are necessary to truly resolve these problems.
But yeah. Body cams are shit. That could have been predicted without them ever entering service. Maybe they'll have a placebo effect of sorts, discouraging officers from using excessive force for fear of documentation? Because nobody's ever been dragged out of sight of dashcams to get the ol' boot in, and there's definitely no way to get the same effective outcome when using bodycams. Still better than the he-said she-said of eyewitness reports, and ain't that a sad standard to exceed.
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And it's still the same old saw. A cop's being a dick? So what? Comply, and if he tries to fuck with you, don't give any excuse. Don't resist, sue after. Plenty of organizations happy to take on police brutality cases, after all. It's shitty that we have to live like that, but if you seriously think that being a cocky smartass is entertaining enough to risk your life, you're touched in the head. If you see a video of someone being "attacked" by cops who are trying to cuff him, and he's not cuffed inside of 2-3 seconds, he's resisting--handcuffs are made to be incredibly easy to put on; if an officer can't get them on, the person they're trying to cuff is resisting.
Re: the last: storytime, folks.
I used to work on a river; the wharf was never a good place at night. I remember getting off shift at around midnight a couple years ago. Right after I clocked out I heard a bunch of screaming start up from where another one of our boats was moored, so I took off that direction. On the way down I passed a couple girls, maybe middle-school age, running the other way, clothes all shredded and shit. A bit further down a couple of my co-workers were laying into some guy. He was a big dude, maybe seven feet tall, and completely out of his gourd on something, ranting about God and stuff.
(As I found out later from the ladies who worked in our office, the girls had been out walking with their parents, who were too plastered to even really know what was happening, and the guy had run up and attacked them, but that's an unrelated fucked up detail.)
It took five us to keep him on the ground while we waited for cops and cracked half-serious jokes about knocking him over the head and dumping him in the water, and he was still almost getting loose. When they got there they tazed him to basically no effect before they tried cuffing him. Despite him being huge, drugged up, and flailing around like hell, it took two cops about ten seconds to get the cuffs on (and then four of them to bodily carry him off)
So there's an entirely useless bit of anecdotal evidence. Handcuffs are intentionally easy to get on. If someone's shouting "I'm not resisting!" but the cops can't get the cuffs on, the guy's full of shit and trying to put on a show for the camera.